1. Field of the Invention
This invention like those of my aforesaid copending applications relates to the production of high solids content aqueous latices with reduced polymer losses by a process which reduces solvent losses, conserves water and minimizes plant effluents thus reducing or eliminating waste material, and aims generally to provide improved method and apparatus combinations therefor.
The processes of the aforesaid applications, with respect to which the inventions of the present application are improvements, have solved a number of the problems of the prior art, by combinations of steps in which an aqueous dispersion of polymer cement is dispersed into a flow of steam or gas comprising steam, but in so doing considerable quantities of solvent and of water saturated with solvent and, in certain instances, of carried-over macromolecular substances have been lost.
2. Description of the Prior Art
In the earlier prior art, synthetic latices of macromolecular material including elastomers and other high polymers were usually those prepared by emulsion polymerization, which can directly yield latices of uniform colloidal particle size. In contrast high polymers made by essentially anhydrous catalyst polymerizations must be converted into latex. In this latter case it has been proposed to prepare aqueous latices of high polymers from solvent solutions thereof by processes of the type which comprise the general steps of (1) providing a dispersion or cement of the polymer in a volatile organic solvent for the polymer, (2) adding to such dispersion water and an aqueous emulsifier therefor and emulsifying the same to produce an emulsion, (3) stripping the volatile organic solvent from the said emulsion, and (4) recovering the resulting latex product. However, in the practical art difficulty has been experienced in attempting to render such proposed processes commercially feasible, inter alia, in that the stripping of solvent from the aqueous emulsion of polymer cement has resulted in losses of valuable materials. These losses have included (a) losses of polymer, (b) losses of solvent and (c) losses of water contaminated with solvent.